In many applications, control of the surface properties is important. For example, controlling the dewetting properties of thin polymer films on an organic or inorganic substrate are important in numerous applications such as sensors, coatings, adhesives, resist layers, lubricating surfaces, and microelectronics. A smooth surface is thought to be wetted by an adsorbed species when van der Waals interactions at the substrate-liquid, liquid-air, and substrate-air interfaces allow the liquid to spread on the surface such that the contact angle is zero or very close to zero. When a thin film is cast on a nonwettable surface for which the interfacial tensions do not favor wetting, dewetting can occur, a process in which the film retracts from the surface, typically forming holes.
Currently, thin amorphous polymer films, such as polystyrene films, are applied to a surface and vitrified to stabilize the film. However, such glassy films are metastable and can spontaneously dewet when exposed to a solvent vapor or heated above the glass transition temperature. Such dewetting of films after exposure to solvent vapor is a current problem in developing sensors to detect nerve agents.
Control of surface properties can also enable new fields of study. For example, glycomics (a field that explores the information content of carbohydrates) has emerged recently. Patterning a surface with carbohydrate microarrays can allow investigation of carbohydrate interactions with viruses, enzymes, cells, antibodies, proteins and the like. However, most current methods for generating carbohydrate microarrays involve either a noncovalent immobilization that becomes less stable as the molecular weight of the carbohydrate decreases, or synthetic methods in which each carbohydrate to be spotted must first be chemically modified.
Accordingly, improved control of surface properties is currently needed to improve various applications, such as sensors, coatings, adhesives, resist layers, lubricating surfaces, microelectronics, etc., and to enable new applications.